Children’s eating habits are established early in life and parents play a major role therein. Pregnancy is a teachable moment for the promotion of healthy eating because many women are concerned about their babies’ health and have frequent contact with healthcare providers. We aimed to investigate the association between diet quality during pregnancy and the offspring. A total of 691 sets of data on pregnant mothers and their 3-year-old offspring were obtained from the Seiiku Boshi cohort study. Dietary intake was assessed using a validated food frequency questionnaire for mothers in mid-to-late pregnancy and a validated diet history questionnaire for Japanese preschool children at the 36-month checkup. Diet quality was scored using the Japanese Food Guide Spinning Top. Maternal diet quality score was categorised into quartiles, and the association between offspring and maternal diet quality score, adjusted for socioeconomic factors, was assessed using multiple linear regression. The total offspring diet quality score showed a linear trend with the maternal diet quality score (the mean increments (confidential intervals) for each quartile were –0.12 (–1.32–1.08), 1.54 (0.34–2.73), and 1.22 (0.03–2.42)). In particular, offspring vegetable dishes scored higher in all quartiles of maternal vegetable dish scores than in the lowest quartile (0.69 (0.21–1.17), 0.97 (0.50–1.45), and 1.36 (0.88–1.83)). A high diet quality score during pregnancy was positively associated with that of offspring, suggesting the importance of nutritional education in pregnant women to improve their diet quality.

Current guidelines provide a universal recommendation on vitamin D intake to prevent insufficiency. However, the relative influence of food, UVB and other factors on serum 25-hydroxyvitamin D (25(OH)D) insufficiency has been poorly investigated in preschool children. We assessed serum 25(OH)D quantities and their association with vitamin D intake using a brief-type self-administered diet history questionnaire for children aged 3–6 years (BDHQ3y), outdoor playing time and background UVB radiation level among 574 36-month-old Japanese children living at latitude 35°N. The average serum 25(OH)D concentration was 23·5 (sd 6·1) ng/ml, and 170 (29·6 %) children had vitamin D insufficiency (<20 ng/ml) despite high consumption of fish. Multiple logistic regression adjusting for social factors showed that when background UVB radiation level was <15 kJ/m2 (monthly average), there was a 1·89 (95 % CI 1·31, 2·74) times higher risk of vitamin D insufficiency, to which vitamin D intake nor time spent outdoors were significantly associated. ANOVA showed that the contribution of the variability in vitamin D intake on the variability of serum 25(OH)D level was 1·8 % of that of UVB exposure. The correlation between vitamin D intake and serum 25(OH)D level was not stronger when limited to measurements in winter. We found that nearly 30 % of 3-year-old Japanese children had vitamin D insufficiency despite high consumption of fish and living at relatively low latitude. We failed to observe an association between vitamin D intake and the risk of vitamin D insufficiency. This may be due to the extremely limited access to vitamin D-fortified food and supplements for children in Japan.

Strategies to manipulate the gut microbiota have been explored for preventing allergy development. We previously showed that dietary supplementation with fructo-oligosaccharide (FOS) reduced 2, 4-dinitrofluorobenzene (DNFB)-induced contact hypersensitivity (CHS) in BALB/c mice. Because the CHS response was negatively correlated with the number of faecal bifidobacteria, particularly Bifidobacterium pseudolongum, the present study aimed to examine whether oral administration of B. pseudolongum affects CHS response. Viable B. pseudolongum was successfully isolated from mouse faeces. Female BALB/c mice were fed a synthetic diet with or without FOS supplementation, and B. pseudolongum (2 × 107 cells) was administered daily throughout the experimental period. Two weeks after starting the test diets, mice received DNFB on the ear auricle twice at 7-d intervals. Conventional cultivation and molecular biological analyses based on 16S rRNA gene sequences showed that administration of FOS and B. pseudolongum resulted in higher excretion of viable bifidobacteria, mainly B. pseudolongum. Although dietary FOS reduced the CHS response as demonstrated by ear swelling, B. pseudolongum administration resulted in a reduction in the initial phase only of the CHS response. B. pseudolongum administration increased hapten-specific IgG1, while dietary FOS decreased IgG2a in sera. Administration of FOS and B. pseudolongum decreased interferon-γ production and increased IL-10 production in cervical lymph node cells restimulated with hapten in vitro. We conclude that B. pseudolongum proliferation in the intestinal tract is partially responsible for the reduction in DNFB-induced CHS response by dietary supplementation with FOS in mice, which may be mediated by the modulation of antigen-induced cytokine production.

Strategies to manipulate the gut microbiota in infancy have been considered to prevent the development of allergic diseases later in life. We aimed to elucidate the effects of maternal dietary supplementation with a prebiotic oligosaccharide on gut microbiota and spontaneously developing atopic dermatitis-like skin lesions in the offspring of NC/Nga mice. Female NC/Nga mice were fed diets either with or without fructo-oligosaccharide supplementation during pregnancy and lactation. After weaning, offspring were fed the diets supplemented with or without fructo-oligosaccharide for 11 weeks in an air-uncontrolled conventional room. Changes in gut microbiota were assessed by denaturing gradient gel electrophoresis of the PCR-amplified 16S rRNA gene. Skin lesions were evaluated by a clinical score and scratching behaviour. Serum antibody levels were measured by ELISA, and expression levels of cytokines and chemokines in lesional tissue were evaluated by quantitative RT-PCR. Maternal supplementation with fructo-oligosaccharide modulated the gut microbiota in sucklings. Although maternal supplementation with fructo-oligosaccharide suppressed the increase in clinical skin severity score and scratching behaviour in offspring, dietary fructo-oligosaccharide after weaning was less effective. The diminution of skin lesions was accompanied by lower serum concentrations of total IgG1 and lower expression levels of TNF-α in the lesional tissue. These data suggest that maternal consumption of fructo-oligosaccharide diminishes the severity of atopic dermatitis-like skin lesions in the offspring of NC/Nga mice.

Our preliminary clinical trial showed that consumption of cooked rice of a Japanese common cultivar Yukihikari improved atopic dermatitis associated with a suspected rice allergy, although the underlying mechanisms remain unclear. We hypothesised that the ameliorating effect of Yukihikari on atopic dermatitis is associated with the gut microbiota. BALB/c mice were fed a synthetic diet supplemented with uncooked and polished white rice powder prepared from one of four different cultivars: Yukihikari, rice A (common rice), rice B (brewery rice) and rice C (waxy rice). Denaturing gradient gel electrophoresis of PCR-amplified 16S rRNA gene fragments showed that the composition of faecal microbiota was different between mice fed Yukihikari and those fed rice A. Analysis of the 16S rRNA clone library and species-specific real-time PCR showed that the abundance of Akkermansia muciniphila, a mucin degrader, tended to be lower in mice fed Yukihikari. The incidence of allergic diarrhoea induced by oral administration of ovalbumin in systemically immunised mice was lower in mice fed Yukihikari, albeit with no difference in serum antibodies specific to ovalbumin. In a separate experiment, serum antibody levels specific to orally administered ovalbumin were lower in mice fed Yukihikari. Additionally, the translocation of horseradish peroxidase in isolated segments of ileum and colon tended to be lower in mice fed Yukihikari, suggesting a reduction in gut permeability in mice fed Yukihikari. These data indicate that changes in the gut microbiota of mice fed Yukihikari could be advantageous in the prevention of food allergy.

The present study introduced a molecular biological approach to demonstrate changes in the composition of intestinal microbiota in neonatal mice. Female BALB/c mice were fed either a control diet or a diet supplemented with fructo-oligosaccharide (FOS) at 50 g/kg diet, and then mated to male mice. A cultivation-independent approach, denaturing gradient gel electrophoresis (DGGE) of the PCR-amplified 16S rRNA gene, was performed to characterise changes in intestinal microbial populations in pups at 0, 7, 14 and 21 d old and their dams. Comparisons of DGGE profiles were performed using the Dice similarity coefficient and the unweighted pair group method with arithmetic mean (UPGMA) cluster analysis based on numbers, positions and intensities of bands. DGGE profiles differed between dams fed control and FOS-supplemented diets. Although profiles in pups on the day of birth showed a high similarity with dams, profiles in 7-d-old pups differed from dams and showed high similarity to littermates. In 14- and 21-d-old pups, profiles again showed high similarity with dams. DGGE profiles in pups were divided into two large clusters of control and FOS-supplemented diet groups in the range of 0- to 21-d-old, suggesting modulation of intestinal microbiota in infants by manipulation of microbiota in dams. The present study shows a useful technique for demonstrating changes in intestinal microbiota and provides a mouse model for modulation of intestinal microbiota in neonatal life.